British prime minister David Cameron announced that the parliamentary Intelligence and Security Committee (ISC), chaired by former foreign secretary Sir Malcolm Rifkind, would investigate, following the disclosure that the two men were known to MI5.

Sir Malcolm has already been briefed by the director general of MI5, Andrew Parker, who will give a preliminary report to the committee next week.

“I had a preliminary briefing from Andrew Parker a couple of days ago. We agreed the committee would receive a written report next week,” Sir Malcolm said.

“What we will be wishing to know is to what extent the intelligence services had any awareness of the two individuals.”

Separately, it was claimed MI5 asked Woolwich murder suspect Michael Adebolajo if he wanted to work for them about six months before the killing, a childhood friend has said.

Abu Nusaybah told BBC Newsnight his friend - one of two men arrested after Drummer Lee Rigby’s murder in London on Wednesday - had rejected the approach.

The BBC said it could not obtain any confirmation from Whitehall sources.

Abu Nusaybah was arrested at the BBC after giving the interview.

Newsnight reporter Richard Watson said after the interview had concluded he left the studio to find officers from the Metropolitan Police counter terrorism unit waiting to arrest Mr Nusaybah.

The police confirmed a 31-year-old man had been arrested in relation to suspected terrorism offences and search warrants were being executed at two homes in east London. But the arrest was not directly related to the murder of Drummer Rigby.

Meanwhile, Mr Rigby’s family paid a touching tribute to the soldier as detectives continued a rapidly-developing investigation into his barbaric killing.

Relatives of Drummer Rigby (25), described their pride in the young father who was hacked to death near Woolwich barracks in south east London.

They spoke for the first time yesterday as detectives continue to question a 29-year-old man on suspicion of conspiracy to murder, as well as suspects Michael Adebolajo and Michael Oluwatobi Adebowale, who remain in hospital after being shot by police when they charged towards armed officers.

Drummer Rigby’s wife Rebecca, mother to their two-year-old son Jack, said through tears that he was “a devoted father”.

Two women — aged 29 and 31 — have both been released without charge after they were held on Thursday on suspicion of conspiracy to murder.

The family also revealed the last text message that Drummer Rigby sent to his mother Lyn.

It said: “Goodnight mum, I hope you had a fantastic day today because you are the most fantastic and one in a million mum that anyone could ever wish for.

“Thank you for supporting me all these years, you’re not just my mum you’re my best friend. So goodnight, love you loads.”

Searches continued at various addresses yesterday — three in south London, one in east London, one in north London and one in Saxilby, Lincolnshire, the former home of Adebolajo.

A neighbour of Adebowale, of Greenwich, south-east London, said that he had always seemed “normal” and was “a nice bloke”.

Drummer Rigby was hit by a car and then attacked with weapons including a knife and a meat cleaver.

He has been formally identified but the cause of his death was not confirmed by a post-mortem examination. An inquest will be opened, Scotland Yard said.

His suspected attackers, who were caught on film in the wake of the murder, were British and of Nigerian descent.

The pair were known to security services and apparently shouted “Allahu akbar” (“God is great”) as they struck.

Hundreds of bunches of flowers were tied to the railings of the barracks at the corner of John Wilson Street and Artillery Place, or placed on the wall, near where Drummer Rigby died.

Among the floral tributes were small wooden crosses bearing poppies, with “In Remembrance” written underneath.

Cards and messages read “Goodnight and God bless young man”, “Such a senseless act” and “A young man taken so tragically”.

A book of condolence has been opened at Woolwich Town Hall, where opening hours will be extended over the bank holiday weekend to allow the public to pay their respects.

Among those coming to pay their respects was British National Party (BNP) leader Nick Griffin, who claimed he had come for personal rather than political reasons.

Mr Griffin’s visit was criticised as “provocative” by Akbar Khan, chairman of the anti-racist and community development organisation Building Bridges.

He said: “It is a provocative action by Nick Griffin, the BNP leader, to go to the place where this young soldier was murdered. All Muslims have come out and condemned this act of violence.

“Given the serene and sad atmosphere prevailing in the country, because of this person’s death, he is being very cynical and exploiting the raw nerves for his benefit, and we say it is just and fair that there should be no politics over dead bodies.

“Whoever is involved in this kind of activity needs to look very carefully at what that person is doing.

“We need to be calm and deal with it in a mature and responsible manner.”

The killing has prompted a huge increase in anti-Muslim incidents, according to the organisation Faith Matters, which works to reduce extremism.

Before the attack about four to eight cases a day were reported to its helpline. However the group said about 150 incidents had been reported in the last few days, including attacks on mosques.